在C＃中比较标志枚举 [英] Comparing enum flags in C#

问题描述

我需要，如果标志被设置的枚举值，类型标记有标示属性内以检测

I need to detect if a flag is set within an enum value, which type is marked with the Flag attribute.

一般它是由这样的：

(value & flag) == flag

但因为我需要通过通用的（有时是在运行时我事件要做到这一点只有一个枚举引用我无法找到使用&放一个简单的方法;运营商目前我做这样的：

But since I need to do this by generic (sometimes at runtime I event have only an "Enum" reference. I can not find an easy way to use the & operator. At the moment I make it like this:

    public static bool IsSet<T>(this T value, T flags) where T : Enum
    { 
        Type numberType = Enum.GetUnderlyingType(typeof(T));

        if (numberType.Equals(typeof(int)))
        {
            return BoxUnbox<int>(value, flags, (a, b) => (a & b) == b);
        }
        else if (numberType.Equals(typeof(sbyte)))
        {
            return BoxUnbox<sbyte>(value, flags, (a, b) => (a & b) == b);
        }
        else if (numberType.Equals(typeof(byte)))
        {
            return BoxUnbox<byte>(value, flags, (a, b) => (a & b) == b);
        }
        else if (numberType.Equals(typeof(short)))
        {
            return BoxUnbox<short>(value, flags, (a, b) => (a & b) == b);
        }
        else if (numberType.Equals(typeof(ushort)))
        {
            return BoxUnbox<ushort>(value, flags, (a, b) => (a & b) == b);
        }
        else if (numberType.Equals(typeof(uint)))
        {
            return BoxUnbox<uint>(value, flags, (a, b) => (a & b) == b);
        }
        else if (numberType.Equals(typeof(long)))
        {
            return BoxUnbox<long>(value, flags, (a, b) => (a & b) == b);
        }
        else if (numberType.Equals(typeof(ulong)))
        {
            return BoxUnbox<ulong>(value, flags, (a, b) => (a & b) == b);
        }
        else if (numberType.Equals(typeof(char)))
        {
            return BoxUnbox<char>(value, flags, (a, b) => (a & b) == b);
        }
        else
        {
            throw new ArgumentException("Unknown enum underlying type " + numberType.Name + ".");
        }
    }


    private static bool BoxUnbox<T>(object value, object flags, Func<T, T, bool> op)
    {
        return op((T)value, (T)flags);
    }

但我不喜欢上房，如果 - else块，所以有没有办法施展这些价值，我可以使用&放大器;运营商或任何其他解决方案来检查呢？

But I don't like the never ending if - else blocks, so is there a way to cast these values that I can use the & operator or any other solution to check this?

推荐答案

我个人认为，看起来很好，因为你已经把它包成一个单一的用的功能。如果出现散在通过整个程序的代码，我认为你会遇到一些问题，但是你所创建的无处不在提高清晰度它的使用量和功能本身就足以做什么的清楚了。

Personally, I think that look fine because you've wrapped it into a single purpose function. If you had that code scattered through an entire program I think you would have some problems, but what you've created improves clarity everywhere it is used and the function itself is clear enough what it does.

只是我当然意见。

您可以但是，使用的关键字，这可能会有点帮助。

You could though, use the is keyword, which might help a little

public static bool IsSet<T>(this T value, T flags) where T : Enum
{ 
    if (value is int)
    {
        return ((int)(object)a & (int)(object)b) == (int)(object)b);
    }
    //etc...

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